If you could lead me to an example with code, that would help me figure out
how to do it for my function


On Wed, Apr 18, 2012 at 3:57 PM, Louis Plough <lplough@usc.edu> wrote:

> I read it, but I guess I don't quite understand which arguments to pass
> panel.groups to get different lm objects based on the two groups within
> Food.
>
>
>
> On Wed, Apr 18, 2012 at 3:44 PM, Bert Gunter <gunter.berton@gene.com>wrote:
>
>> Please read ?panel.superpose  again and pay attention to the
>> panel.groups argument, where this can be specified.
>>
>> -- Bert
>>
>> On Wed, Apr 18, 2012 at 12:34 PM, Louis Plough <lplough@usc.edu> wrote:
>> > Hi,
>> > I am trying to use xyplot to plot the relationship between size and day
>> > (y~x) by a food factor that has two levels, low and high. I have 3 reps
>> per
>> > factor/day.  I want the plots from each food treatment on the same
>> axiss,
>> > so I used this code:
>> >
>> > xyplot(Size ~ Day, groups = Food, data = louis.data.means,col=1,
>> > pch=c(1,17),
>> > panel=function(x,y,groups,...){
>> > panel.superpose(x,y,groups,...)
>> > tmp.lm<-lm(y~x)
>> > panel.abline(tmp.lm)
>> > panel.text(2, 250, label=format(tmp.lm$coefficients[2], digits=4),
>> pos=4)
>> > }
>> > )
>> > This produces a graph of the two treatments (open circles for the low
>> food
>> >  vs triangles for the high food) on the same plot, but only one
>> regression
>> > line (and slope)  which seems to splits the difference between the two
>> > factors (treats them as the same data set).  I would like to produce a
>> > separate regression line for the data from each of the two factors (high
>> > food vs low food).
>> >
>> > Is there a way to subset the lm by the factor "food"?
>> >
>> > Louis
>> >
>> >        [[alternative HTML version deleted]]
>> >
>> > ______________________________________________
>> > R-help@r-project.org mailing list
>> > https://stat.ethz.ch/mailman/listinfo/r-help
>> > PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>>
>>
>>
>> --
>>
>> Bert Gunter
>> Genentech Nonclinical Biostatistics
>>
>> Internal Contact Info:
>> Phone: 467-7374
>> Website:
>>
>> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
>>
>
>

	[[alternative HTML version deleted]]

